The present invention relates to a multi-layer body structure for the reinforcement of a panel and to a method of reinforcing a panel with the multi-layer body structure.
More particularly, the invention relates to a reinforcing member adaptable to the reinforcement of a panel formed of metal, plastic or sheet molding compound.
Such multi-layer structures may comprise a first, fiber-reinforced layer, e.g. a glass fiber tissue impregnated with a thermosetting resin material, one surface thereof being coated with a second layer consisting of a further, thermosetting resin, said second layer serving as an adhesive layer. A multi-layer body member of this kind may be used to reinforce flat or curved panels like, for instance, sheet metal portions by placing a piece of the multi-layer body member with its sticky resin surface onto the sheet metal portion to be reinforced and subsequently subjecting it to a heat treatment. Thereby, on the one side, an adhesion of the multi-layer body member to the sheet metal portion is effected and, on the other side, the resin layers are cured such that a stiff connection between the sheet metal portion and the fiber reinforced layer results. In this way, an essential stiffening of the sheet metal portion may be achieved in a very simple manner without the disadvantage of substantially increasing the weight of the panel to be reinforced.
In order to make sure that the multi-layer body member can easily be applied to the sheet metal portion to be reinforced, the resin layer usually has a sticky surface such that the applied multi-layer body member adheres in the required position to the sheet metal portion until it is subjected to a heat treatment. However, one is forced to protect the sticky resin surface of the multi-layer body member up to the moment when it is used in order to protect the sticky resin surface from contamination and, further, in order to enable a plurality of multilayer body members to be stacked. In the prior art, such protection is in the form of a suitably treated paper sheet or a protection foil which can be removed from the multi-layer body member surface immediately prior to its application.
One of the most important disadvantages thereby is that the removal of the protection paper or the protection foil is an undesired additional operation step which hardly can be performed automatically. Particularly in the field of automobile construction in which such multi-layer body members are widely used and in which an important goal consists in the automation of as many operation steps as possible, this operation of removing the protection paper or the protection foil is considered as an undesired and time-consuming job which can be performed only by a human operator.